Fill anchor holes with low modulus polyurethane sealant filler and install anchors.
Fill anchor holes with epoxy filler and install anchors with ½ inch (13 mm) long 60 durometer elastomeric sleeve at the back surface of the stone.
PCI recommends preventing bond between stone facing and precast concrete to minimize bowing, cracking, and staining of stone. Retain one of two subparagraphs below.
Install 6 to 10 mil polyethylene sheet to prevent bond between back of stone facing and concrete substrate.
Install 1/8 inch (3 mm) polyethylene-foam bond breaker to prevent bond between back of stone facing and concrete substrate. Maintain minimum projection requirements of stone anchors into concrete substrate.
PCI recommends anchor spacing be determined prior to bidding. Retain below if precaster is to test stone anchors for shear and tension. ASTM E488 is preferred as ASTM C1354 does not include the influence of the precast concrete backup.
Stone Anchor Shear and Tensile Testing: Engage a certified testing laboratory acceptable to the Architect to evaluate and test the proposed stone anchorage system. Test for shear and tensile strength of proposed stone anchorage system in accordance with ASTM E 488 or ASTM C 1354 modified as follows:
Prior to testing, submit for approval a description of the test assembly (including pertinent data on materials), test apparatus and procedures.
Test 12-by-12 inch (300 by 300 mm) samples of stone affixed to testing apparatus through proposed anchorages. Provide 2 sets of 6 stone samples each. One set for shear load testing and the other set for tensile load testing.
Test stone anchors of the sizes and shapes proposed for the installation.
a. Test the assembly to failure and record the test load at failure. Record the type of failure,
anchor pull-out or stone breakage, and any other pertinent information, in accordance with
the requirements of ASTM E 488. In addition, submit load deflection curves of each test
Minimum Anchor Spacing: Anchor spaced not less than 6 inches (152 mm) from an edge with not more than 24 to 30 inches (610 to 760 mm) between anchors depending on the local building code and wind loading.
Cast-in Anchors, Inserts, Plates, Angles, and Other Anchorage Hardware: Fabricate anchorage hardware with sufficient anchorage and embedment to comply with design requirements. Accurately position for attachment of loose hardware and secure in place during precasting operations. Locate anchorage hardware where it does not affect position of main reinforcement or concrete placement.
Weld headed studs and deformed bar anchors used for anchorage according to AWS D1.1 and AWS C5.4, “Recommended Practices for Stud Welding.”